The Siege of Stralsund was a siege laid on Stralsund by Albrecht von Wallenstein's Imperial Army during the Thirty Years' War, from May to 4 August 1628. Stralsund was aided by Denmark and Sweden, with considerable Scottish participation. The lifting of the siege ended Wallenstein's series of victories, and contributed to his downfall. The Swedish garrison in Stralsund was the first on German soil in history. The battle marked the de facto entrance of Sweden into the war.